The ornamental design for a “LED bulb,” as shown and described.
FIG. 1 is a perspective view showing my design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a left side elevational view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is a additional perspective view thereof.
The LED bulb of the present invention may be coupled with one or more power cables or brackets which are depicted in broken lines and form no part of the design.